Baking apparatus and method for baking edible products

ABSTRACT

Baking apparatus for baking edible products located on a conveying surface and preferably traveling along a conveyor track, comprising a number of electric infrared radiators arranged above the conveyor track. The infrared radiators each comprise at least one spiral filament having a gastight, infrared radiation-transmitting, breakable casing, in particular a glass casing. The baking apparatus further comprises monitoring means for monitoring breakage of the casings of the infrared radiators. The invention also relates to a method for baking an edible product by means of an electric infrared radiator having a breakable casing.

This application is a divisional application of U.S. application Ser.No. 10/203,466, filed Oct. 21, 2002, now U.S. Pat. No. 7,231,871, whichclaims priority based on an International Application filed under thePatent Cooperation Treaty, PCT/NL00/00083, filed on Feb. 10, 2000.

FIELD OF THE INVENTION

The invention relates to a baking apparatus for baking edible productslocated on a conveying surface and preferably traveling along a conveyortrack.

BACKGROUND OF THE INVENTION

It is observed that in this context, “baking” should be understood tomean at least the complete or partial browning and/or the complete orpartial cooking of a product.

In the food industry, there is currently an increasing interest forproducts which are ready to be consumed by a consumer or which requireonly a short preparation time for consumption. Examples hereof arepastas or pieces of meat which are completely or partially pre-baked andwhich can be prepared by a consumer by heating briefly, for instance byheating in a microwave oven.

During manufacture of such products, it is important that the bakingprocess can be accurately controlled. With so-called ready-to-eat meals,it is for instance important that the different components of the mealbe pretreated in such a manner that the remaining preparation time ofthe components is substantially the same and that after a briefpreparation by the consumer, each of the components of the meal has theproper degree of cooking. In the case of perishable products, it isfurther important that it can be predicted with great certainty whichdegree of cooking is reached, because the storage life of the product,i.e. the safe time interval between the moment when the product isprebaked and the moment when it should have been consumed, can therebybe increased. In particular for meat products, at least meat-containingproducts, the above problems play a substantial part.

Conventionally, products, for instance pieces of meat, are prebaked bymoving them through a trough of boiling oil by means of a conveyortrack. A drawback hereof is that the baking process cannot be controlledfast enough. In particular, the temperature of the oil cannot beadjusted fast enough when, suddenly, many products are immersed in theoil or when, suddenly, the size of the products to be baked varies.Consequently, as far as the degree of cooking is concerned, there shouldalways be observed an ample safety margin, as a result of which thestorage life of a product is relatively short and a product, afterpreparation by a consumer, is often overdone.

Further, a drawback of baking with oil is that a product losesrelatively much moisture during baking. This reduces the weight of theproduct, thereby increasing the costs per unit of weight of the endproduct. Further, an oil-baked product contains relatively much fat,which is currently usually considered undesirable by the consumer. Inaddition, the oil affects the taste of the product, as a result of whichhigh requirements have to be imposed on the quality of the oil.Consequently, the oil has to be replaced often. This does not only havethe drawback that large quantities of new oil have to be purchased, butalso that large amounts of fouled oil have to be discharged. Moreover,keeping the oil at the proper temperature requires relatively muchenergy.

To avoid these drawbacks, it has already been proposed, for instance, toprecook pieces of meat by means of steam. A drawback hereof is that themeat assumes an grey color, which is usually experienced as unappealingby the consumer. Particularly for products which are to beconsumer-prepared by microwave oven only, this grey appearance hasproved to be a major problem from the point of view of selling.

SUMMARY OF THE INVENTION

The object of the invention is to provide a baking apparatus for bakingedible products traveling along a conveyor track, which apparatus doesnot have the above-mentioned drawbacks. To that end, a baking apparatusaccording to the invention is characterized in that it comprises anumber of electric infrared radiators arranged above the conveyor track,each infrared radiator comprising at least one spiral filament having agastight, infrared radiation-transmitting, breakable casing, inparticular a glass casing, and further comprises monitoring means formonitoring breakage of at least one of the casings.

The effect achieved through the use of infrared radiation is that anedible product can be baked contactlessly. Thus, the use of oil can beminimized or even be omitted completely, while the product obtains anappealing appearance all the same. Through the use of a gastight casingof the spiral filament, it is achieved that a spiral filament can beused of which the intensity of the emitted radiation is quickly andaccurately settable, so that the baking process can be controlled veryeffectively. In particular, the supply of radiation can thus becontrolled so that radiation is supplied only when needed, which enablesenergy saving. Further, the degree of cooking of a product can thus beproperly predicted. A further advantage of the casing is that itprotects the spiral filament, for instance against fouling. The use ofmonitoring means prevents, in the event of breakage of the casing, partsof the casing, such as glass fragments, from getting between theproducts unnoticed.

Preferably, infrared radiators of the so-called short-wave type and/orthe so-called fast medium-wave type are used. These types of infraredradiators will be explained in more detail hereinbelow.

In an advantageous embodiment, a baking apparatus according to theinvention is characterized in that the monitoring means comprisedetection means for detecting, during use, the electric power taken upby an infrared radiator and/or current passing through an infraredradiator. Preferably, the detection means comprise a measuringtransducer for measuring the power taken up by an infrared radiatorand/or the intensity of the current passing through an infraredradiator. Indeed, in the event of breaking of the casing, thegastightness will be lost and the spiral filament will burn throughquickly, due to the oxygen present in the ambient air. Through detectionor measuring of the power taken up or the current intensity, it isachieved that the burning-through of the spiral filament can bedetermined, so that breakage of the casing can be monitored. Through theuse of detection, it is readily detected whether or not any power istaken up, or whether or not there passes a current. Measuring has theadvantage that intermediate conditions can be established as well, forinstance a deviation of the power actually taken up relative to a powerthat is desirably taken up.

In another embodiment, a baking apparatus according to the invention isfurther characterized in that it comprises interruption means forinterrupting the travel of the products along the conveyor track andcontrol means for interrupting the travel of the products by theinterruption means when glass breakage is monitored by the monitoringmeans. It is thus provided that each time when a casing is broken, thebaking apparatus can at least be partially cleaned and that fragmentsand possibly contaminated products can be removed from the conveyortrack.

In yet another embodiment, a baking apparatus according to the inventionis characterized in that it further comprises collecting means, disposedbetween the conveyor track and the infrared radiators, for collectingthe parts of a casing in the event of breaking of the casing. It is thusprovided that the chance of fragments mixing with at least the productsintended for consumers is reduced considerably.

The invention also relates to a method for baking an edible product, inparticular a piece of meat, by means of at least one electric infraredradiator, wherein during a first step, the intensity of the infraredradiator is controlled so that per unit of time, more radiation energyis supplied to the surface of the product than can be transmitted to theinterior of the product, and wherein during a second step, the intensityof the infrared radiator is controlled so that per unit of time, at themost as much radiation energy is supplied to the surface of the productas can be transmitted to the interior of the product. Preferably, anelectric spiral filament disposed in a gastight environment is used, andthe temperature of the surface of the product is measured and further,depending on the temperature measured, the intensity of the infraredradiation is controlled. Thus, it is not only achieved that the productcan be provided with an attractive outer layer, but also that a thinouter layer of the product can at least be partially seared up, wherebyevaporation of moisture from the interior can be prevented. This reducesthe weight decrease of the product during baking, which results in alower cost price per unit of weight of the finished product.

Further elaborations of advantageous embodiments of the baking apparatusand the method according to the invention are described in thesubclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be specified with reference to anexemplary embodiment shown in a drawing. In the drawing:

FIG. 1 is a schematic representation of a first embodiment of a bakingapparatus;

FIG. 2 is a diagram showing a number of functions of the bakingapparatus of FIG. 1;

FIG. 3 is a schematic longitudinal section of a second embodiment of abaking apparatus;

FIG. 4 is a schematic side elevation of a third embodiment of a bakingapparatus; and

FIG. 5 is a cross section of the baking apparatus of FIG. 4, taken onthe line V-V.

DETAILED DESCRIPTION OF THE INVENTION

It is observed that the Figures are only schematic representations ofpreferred embodiments of the invention. In the Figures, identical orlike parts are designated by corresponding reference numerals.

With reference to FIGS. 1 and 2, a baking apparatus 1 is schematicallyshown therein for baking edible products 4 which travel in a directionof travel 2 along a conveyor track 3 designed as an endless conveyorbelt. Arranged above the conveyor track 3 are a number of electricinfrared radiators 5. The infrared radiators are each provided with aspiral filament 6 having a gastight, infrared radiation-transmitting,breakable casing 7. The baking apparatus 1 comprises monitoring means 8for monitoring breakage of the casings 7. The monitoring means 8 arehere designed as transducers 10 provided at the electric circuit 9 formeasuring, through induction, the electric power taken up by thedifferent infrared radiators 5. Of course, the transducers may also beincorporated into the electric circuit. The transducers 10 are connectedto control means 11 designed as, for instance, a PLC. By the controlmeans 11, interruption means 12 can be actuated for interrupting thetravel of the products 4. The interruption means 12 are here designed asa relay which interrupts the current to the electric drive motor 13 ofthe conveyor belt 13.

In the case of breakage of a casing 7, the spiral filament 6 will beexposed to the ambient air. Due to the reaction with the oxygen presentin the ambient air, the spiral filament 6 will quickly burn through andno longer conduct any current, which is expressed in a decrease of theelectric power taken up by the infrared radiator 5. If such decreaseoccurs, this is monitored by the monitoring means 8 and transmitted tothe control means 11. Next, the control means 11 actuate theinterruption means 12, causing the travel of the products 4 to beinterrupted. Preferably, the current supply to the infrared radiators 5is interrupted as well. Now, the radiator 4 whose spiral filament 6 isbroken can be replaced. If the casing 7 is broken, possibly contaminatedproducts 4 are removed from the conveyor track 3 and, subsequently, theportion of the conveyor track 3 located adjacent the radiator 4 iscleaned. Then, by the control means 11, the travel of the products 4 canbe continued again and the current supply can be restored.

The measuring transducers 10 can also be coupled to indicating means 14for indicating an infrared radiator 5 with a broken casing 7. Theindicating means can, for instance, be designed as a lamp or a display.

Between the conveyor track 3 and the infrared radiators 5, collectingmeans 15 may be disposed for receiving parts of a casing 7 in the caseof breakage thereof. The collecting means 15 can be designed as aplastic film, preferably a film having a low absorption of infraredradiation. A suitable film is, for instance, the polyamide film ofDuPont® commercially available under the tradename Kapton®.

Preferably, the casings 7 are elongated and extend substantiallytransverse to the direction of travel 2. The effect thus achieved isthat when a casing 7 is broken, the conveyor track 3 is possibly fouledwith fragments over a limited part of its length only. It is observedthat in such arrangement, it is not necessary that the products 4 travellinearly along the conveyor track 3. The conveyor track 3 may, forinstance, be circular, while the infrared radiators 5 may be arranged inradial direction. A second advantage achieved by the arrangementtransverse to the direction of travel 2 is that the radiators 5 form aradiation field in which any inhomogeneities in the intensity of thefield lie in the direction of travel 2, so that each product 4, whentraveling through the radiation field, in principle receives the sameamount of radiation.

The baking apparatus 1 can further comprise regulating means 16 forregulating the intensity of the infrared radiators 5. The intensity can,for instance, be regulated for each infrared radiator 5 separately orfor a group of radiators 5 by means of electronic power regulatorscooperating with the control means 11.

Detection means 17 can also be arranged along the conveyor track 3 fordetecting, during use, whether a product 4 is present at a givenlocation. Such detection means 17 can, for instance, be designed as alight source cooperating with a photocell. By coupling the detectionmeans 17 to the control means 11, it can be effected that an infraredradiator 5 is switched off when no product 4 has been present for sometime. In this manner, much energy can be saved. Of course, it may beadvantageous to couple the detection means forwards to the control, sothat the infrared radiators can be activated already before the passingof a product, for instance for compensating the heating-up time.

The baking apparatus 1 can also be provided with measuring means 18 formeasuring, during use, the temperature of a product 4. Such measuringmeans 18 can advantageously be designed as contactless pyrometerswhereby the temperature of the surface of a product 4 can be measured.Such pyrometers are of standard commercial availability and are hencenot further specified here.

Through coupling of the measuring means 18 to the control means 11, itcan advantageously be effected that when a product 4 is detected by thedetection means 17 and when, by the measuring means 18, the temperatureof the product 4 is measured, the intensity of one or more of theinfrared radiators 5 is regulated by the regulating means 16, dependingon a set value. Such value can, for instance, depend on the type ofproduct 4 or on the processing which a product 4 has to undergo, andcan, for instance, be stored in a memory 19 coupled to the control means11. In this manner, the degree of cooking of a product 4 can beaccurately controlled and energy can be saved.

By means of such baking apparatus 1, during a first step, the intensityof the infrared radiator can be controlled in such a manner that perunit of time, more radiation energy can be supplied to the surface of aproduct than can be transmitted to the interior of the product. Suchfirst step can be carried out adjacent the beginning of the conveyortrack 3. By simultaneously measuring the temperature of the surface ofthe product, a thin layer of the outer surface of the product can beseared up to prevent loss of moisture during the further baking process.Due to the fast controllability of the infrared radiator 5, the outerlayer of a product may be prevented from burning. During a second step,the intensity of the infrared radiator can be controlled in such amanner that at the most as much radiation energy is supplied to thesurface of the product as can be transmitted to the interior of theproduct. It is thus effected that the product can subsequently be heatedup as quickly as possible without involving any loss of moisture. Byturning the product, the lower part of the surface of the product can beturned up, allowing it to be seared up as well.

In the baking apparatus 1, infrared radiators 5 of the so-calledshort-wave type or the so-called fast medium-wave type are preferablyused. Such infrared radiators are characterized by a relatively shortheating-up time during switching on and a relatively short cooling-downtime during switching off. Depending on the type of infrared radiator,the heating-up time can vary from less than 15 seconds to even less than1 second.

Hereinbelow, an explanation of the infrared radiators will be given. Itmay be understood that this explanation serves by way of illustrationonly.

An infrared radiator of the short-wave type has a shorter heating-uptime and a higher end temperature of the spiral filament than a radiatorof the fast medium-wave type. During heating up, the temperature of thespiral filament of an infrared radiator of the fast medium-wave typerises from, for instance, less than 100° C. t) a maximum of about1500-1700° C. in about 4 seconds. With an infrared radiator of theshort-wave type, the maximum temperature of about 1900-2100° C. is, forinstance, realized within 1 second.

For an infrared radiator 5 of the fast medium-wave type, the maximumintensity of the infrared radiation lies in the medium-wave infraredrange, i.e. radiation of a wavelength approximately between 1.4 and 2.5μm, in particular about 1.5 μm. For a short-wave radiator, this lies inthe short-wave infrared range, i.e. radiation of a wavelength betweenabout 0.9 and 1.6 μm, in particular about 1.4 μm.

Depending on the type of product and the desired treatment, a particulartype of infrared radiator can be selected or a combination of theradiator types can be made. Advantageous infrared radiators of the fastmedium-wave type are infrared radiators of the 1400 series marketed bythe firm Heraeus. Advantageous infrared radiators of the short-wave typeare the infrared radiators of the 1700 series of the firm Heraeus. Suchinfrared radiators have a casing of quartz glass and a reflector layerapplied by vaporization, so that the infrared radiation can be bundledin the direction of the conveyor track 3.

Further, the control means 11 can comprise means for registering thelighting period of a infrared radiator 5. Thus, a warning signal can begenerated by the control means 11 when the chance of breaking of thecasing has increased to above a given value, for instance when 90% ofthe expected lifetime of the infrared radiator has passed. Consequently,the chance that the infrared radiator is replaced in time, i.e. beforethe occurrence of breaking, becomes greater, as a result of which thechance that products intended for consumers become contaminated withparts of the casing is further reduced.

The baking apparatus 1 can also be provided with means 20 for generatingan air flow between the infrared radiators 5, for instance a fan. Theeffect thus achieved is that the air around the infrared radiators 5 isevenly distributed, so that the infrared radiators 5 cannot only becooled, but the radiation emitted by the infrared radiators 5 can alsobe distributed over the radiation area more evenly. As a result, unevendiscoloring of the surface of the product to be baked can be prevented.This is important in particular during the baking of light-coloredproducts, such as fillets of chicken. Preferably, the radiators 5 areaccommodated in a light box 21. The light box 21 can advantageously beprovided with partitions 22 for distributing the air flow along thedifferent radiators 5. If necessary, on the side facing the conveyortrack 3, the light box can be shut off by means of the above-mentionedplastic film.

FIG. 3 shows an embodiment of the baking apparatus 30 for baking edibleproducts 4 traveling along a conveyor track 3 in a direction of travel2, wherein the conveyor track is designed as an endless conveyor belt 31having a tunnel-shaped housing 32 which surrounds the conveyor belt 31.The conveyor belt 31 comprises four parts 33, 34, 35 and 36. Arrangedbetween the parts 34 and 35 is a turning station 37 for turning theproducts 4, for instance when the product 4 is a hamburger to be bakedon two sides. Arranged between the parts 33 and 34 and the parts 35 and36 respectively are operating cylinders 38 whereby a height differencecan be set between the parts 33 and 34 and the parts 35 and 36respectively. It is thus effected that smaller products, such as shoarmameat, can be turned more often. To enhance coloring of the products, aslight amount of oil can be sprayed onto the products by means of atubular atomizer 39. There is further provided a washing installation 40for washing the return part of the conveyor belt 31 during the returntravel. Preferably, directly upstream of the washing installation 40, ablower is arranged for blowing the conveyor belt clean.

By means of the baking apparatus 30, the products 4 can, for instance,be seared up at their upper surfaces by means of a first group ofradiators 45 and cooked by means of a second group of radiators 46.After turning of the products 4 by means of the turning station 37, theproducts can be further seared up by a third group of radiators 47 andfurther cooked by a fourth group of radiators 48. It is observed that itmay be advantageous to wholly sear up the products 4 directly, forinstance by turning the products earlier and searing them up on twosides before the interior is cooked.

The temperature of the surface of the products 4 can be measured bymeans of pyrometers arranged adjacent the places where the surface ofthe products is seared up, i.e. at the first group of radiators 45 anddownstream of the third group of radiators 47. By means of thepyrometers disposed adjacent the third group of radiators 47, it is alsopossible to determine the degree of cooking on the basis of thetemperature directly after turning. Adjacent the fourth group ofradiators 48, a final measuring of the surface temperature can takeplace for checking the degree of cooking.

Referring to FIGS. 4 and 5, a baking apparatus 41 is shown thereinhaving a tunnel-shaped housing built up from segments 42. The segments42 are each provided with a cover part 43 supporting a number ofinfrared radiators 5. The cover part 43 is pivotable relative to an axis44 extending substantially in direction of travel 2, so that the coverpart is pivotable between a first position in which the radiators 5 arelocated above the conveyor track 3 and a second position in which theradiators 5 are accessible for maintenance operations. On a verticalside thereof, the segments 42 are provided with side panels 45. The sidepanels 45 are pivotable relative to a substantially vertical pivotalaxis between a first position in which the tunnel-shaped housing 32 isclosed off so as to be radiation-proof, and a second position in whichthe interior of the segment is released. Thus, in the second position,the interior of the segment is accessible. The effect thus achieved isthat when the casing 7 of a radiator 5 located in the cover part 43 of asegment 42 is broken, the products present in that segment can beremoved and the interior of the segment 42 can be cleaned.

Disposed between the upper part and the lower part of the conveyor beltare plate-shaped elements 49 for collecting juices released from theproducts 4 during baking. The plate-shaped elements 49 can, forinstance, be included as a drawer in the interior of the segments, sothat they can be pulled out for cleaning. Preferably, the plate-shapedelements 49 slope downwards, so that a film of water can flow over theelements 49 for discharging the released juices.

It is observed that the invention is not limited to the above-describedpreferred embodiments. Many variations thereof are possible.

Thus, it is for instance possible to apply other types of monitoringmeans, for instance detection means for detecting an interruption of aconductor provided on the outside of the casing, for instance forbreakage of the gold reflector layer applied by vaporization. It is alsopossible to detect the passing of casing parts by means of photocells,to scan the casing by means of waves, to measure the gas pressure in theconductor or to measure the presence/intensity of the emitted radiation.Further, it is possible to design the conveyor track differently, forinstance as a chain.

These and many other variations will be directly understood by anyoneskilled in the art. Such variations are considered to fall within theframework of the invention as set forth in the following claims.

1. A method for baking an edible product comprising the steps of: conveying the edible product along a conveyor track using a motor; controlling the intensity of an electric infrared radiator disposed adjacent the conveyor track during a first heating step so that, per unit of time, more radiation energy is supplied to the surface of the product than can be transmitted to the interior of the product, wherein the infrared radiator comprises a spiral filament disposed in a gastight, infrared radiation-transmitting casing; controlling the intensity of the infrared radiator during a second heating step so that, per unit of time, at the most as much radiation energy is supplied to the surface of the product as can be transmitted to the interior of the product; monitoring breakage of the infrared radiator casing using a transducer, the transducer measuring the electric power taken up by the infrared radiator and transmitting a signal to a controller upon a decrease of the electric power; and automatically stopping the conveying of the edible product along the conveyor track with the controller upon monitoring a breakage of the casing of the infrared radiator.
 2. A method for baking an edible product as defined in claim 1, wherein the controller automatically interrupts electric current to the motor by actuating a relay connected to the motor for automatically stopping the conveying of the edible product along the conveyor track.
 3. A method for baking an edible product as defined in claim 1, further comprising the step of indicating a breakage of the casing with an indicating means upon monitoring a breakage of the casing of the infrared radiator.
 4. A method for baking an edible product as defined in claim 1, wherein a plurality of infrared radiators are used and the method further comprises the step of automatically interrupting current to all infrared radiators upon monitoring a breakage of the casing of any one infrared radiator.
 5. A method for baking an edible product as defined in claim 1, wherein the infrared radiator is disposed above the conveyor track, and the method further comprises the step of preventing parts of a broken casing from reaching the conveyor track with a collecting means.
 6. A method for baking an edible product as defined in claim 5, wherein the collecting means is a plastic disposed between the infrared radiator and the conveyor track.
 7. A method for baking an edible product as defined in claim 1, further comprising the steps of: detecting whether an edible product is present at a given location along the conveyor track with a detection means, the detection means being connected to the controller; and automatically interrupting current to the infrared radiator with the controller upon detecting the absence of an edible product on the conveyor track after a predetermined time.
 8. A method for baking an edible product as defined in claim 7, wherein the detection means comprises a light source cooperating with a photocell.
 9. A method for baking an edible product as defined in claim 1, further comprising the steps of: measuring the temperature of the surface of the product with a pyrometer; and varying the intensity of the infrared radiator depending on the temperature measured by the pyrometer.
 10. A method for baking an edible product as defined in claim 1, further comprising the steps of: detecting whether an edible product is present at a given location along the conveyor track with a detection means, the detection means being connected to the controller; measuring the temperature of the surface of a detected product with a pyrometer; varying the intensity of the infrared radiator depending on the temperature measured by the pyrometer; and automatically interrupting current to the infrared radiator with the controller upon detecting the absence of an edible product on the conveyor track after a predetermined time.
 11. A method for baking an edible product as defined in claim 1, further comprising the steps of: registering the lighting period of the infrared radiator with the controller; and generating a warning signal with the controller when the registered lighting period of the infrared radiator has reached a predetermined value indicating that that the expected lifetime of the infrared radiator has passed.
 12. A method for baking an edible product comprising the steps of: conveying the edible product along a first conveyor track; controlling the intensity of a first set of electric infrared radiators disposed above the first conveyor track during a first heating step so that, per unit of time, more radiation energy is supplied to a first surface of the product than can be transmitted to the interior of the product, so that the first surface of the edible product is seared; controlling the intensity of a second set of infrared radiators disposed above the first conveyor track, downstream of the first set of infrared radiators, during a second heating step so that, per unit of time, at the most as much radiation energy is supplied to the first surface of the product as can be transmitted to the interior of the product, so that the interior of the product is cooked; receiving the product from the first conveyor track with a turning station disposed downstream of the first conveyor track; turning the product over with the turning station; placing the product on a second conveyor track with the turning station so that the first surface of the product is placed against the second conveyor track, the second conveyor track being disposed downstream of the turning station; controlling the intensity of a third set of electric infrared radiators disposed above the second conveyor track during a third heating step so that, per unit of time, more radiation energy is supplied to a second surface of the product than can be transmitted to the interior of the product, so that the second surface of the edible product is seared; and controlling the intensity of a fourth set of infrared radiators disposed above the second conveyor track, downstream of the third set of infrared radiators, during a fourth heating step so that, per unit of time, at the most as much radiation energy is supplied to the second surface of the product as can be transmitted to the interior of the product, so that the interior of the product is cooked.
 13. A method for baking an edible product as defined in claim 12, wherein the infrared radiators comprise a spiral filament disposed in a gastight, infrared radiation -transmitting casing, and wherein the method further comprises the steps of: monitoring breakage of the infrared radiator casings using a transducer, the transducer measuring the electric power taken up by the infrared radiators and transmitting a signal to a controller upon a decrease of the electric power; and automatically stopping the conveying of the edible product along the conveyor tracks with the controller upon monitoring a breakage of the casing of the infrared radiator.
 14. A method for baking an edible product as defined in claim 13, wherein the controller automatically interrupts electric current to the motor by actuating a relay connected to the motor for automatically stopping the conveying of the edible product along the conveyor track.
 15. A method for baking an edible product as defined in claim 12, further comprising the steps of: measuring the temperature of at least one of the first and second surfaces of the product with a pyrometer; and varying the intensity of at least one of the first, second, third and fourth sets of infrared radiators depending on the temperature measured by the pyrometer.
 16. A method for baking an edible product comprising the steps of: conveying the edible product along a conveyor track; controlling the intensity of an electric infrared radiator disposed adjacent the conveyor track during a first heating step so that, per unit of time, more radiation energy is supplied to the surface of the product than can be transmitted to the interior of the product; controlling the intensity of the infrared radiator during a second heating step so that, per unit of time, at the most as much radiation energy is supplied to the surface of the product as can be transmitted to the interior of the product; measuring the temperature of the surface of the product with a pyrometer; and varying the intensity of the infrared radiator depending on the temperature measured by the pyrometer; wherein the infrared radiator comprises a spiral filament disposed in a gastight, infrared radiation-transmitting casing, and wherein the method further comprises the steps of: monitoring breakage of the infrared radiator casing using a transducer, the transducer measuring the electric power taken up by the infrared radiator and transmitting a signal to a controller upon a decrease of the electric power; and automatically stopping the conveying of the edible product along the conveyor track with the controller upon monitoring a breakage of the casing of the infrared radiator.
 17. A method for baking an edible product as defined in claim 16, wherein the controller automatically interrupts electric current to the motor by actuating a relay connected to the motor for automatically stopping the conveying of the edible product along the conveyor track. 